Smaller plates, fewer calories? The latest study shows one way to fight childhood obesity may be to shrink the size of the dinner plate.

According research published in the journal Pediatrics, first-graders served themselves more and downed more calories when they used a large plate instead of a smaller one.

Simply advising parents — and kids — to eat less and exercise more hasn’t turned the childhood obesity epidemic around. And it’s obvious why: high-calorie foods are plentiful, not to mention sugary beverages that can also pack on the pounds. Portion sizes have ballooned over the past several decades. And at least one study reported that plate sizes have increased too. With one in three U.S. kids now defined as overweight or obese, researchers at Temple University decided to study how effective shrinking plate sizes could be in keeping appetites in check.

The theory made sense; previous research found that adults pile on more food and eat more calories when their bowls are bigger. Would the same hold true for children, wondered Jennifer Orlet Fisher, an associate professor of public health at Temple’s Center for Obesity Research and Education.

She and her colleagues zeroed in on two classes of first-graders at a private school in north Philadelphia. Over eight days, the 42 students helped themselves to a buffet set up by the researchers. It was self-serve, a plus for the 7-year-olds, and the menu stayed essentially the same to eliminate the possibility that kids might load up on mac and cheese but go easy on sautéed kale. Their choices: penne or chicken nuggets, applesauce and mixed veggies.

On half the days, the kids used plates that were 7 ¼ inches in diameter — about the size of a salad plate — and on the other days they were provided with dishes the size of a dinner plate at 10 ¼-inches in diameter. Their plates were weighed before and after they ate.

The kids served themselves 90 calories more on days when they used bigger dishes; they ended up consuming about half those calories and leaving the rest uneaten, which was still more than what they ate on days they used the smaller plates. “Studies show that when kids serve themselves more, they are going to eat more,” says Fisher, the study’s lead author.

Fisher doesn’t think that simply swapping a large plate for a small plate is the answer to controlling eating. But the good news is that it’s much easier to change kids’ eating habits than those of adults. Children are more likely to eat only when they feel hungry, while adults are more influenced by other factors including the cost of food and the emotions that can prompt mindless noshing. “Kids are much less complicated eaters than adults are,” says Fisher.

As a mom of twin 8-year-old boys, she empathizes with the struggle many parents face when confronted with scraping up a healthy meal for the family. Moms and dads don’t have time to study, interpret and implement dietary recommendations or follow nutritional guidelines, but switching to smaller plates might be something they can easily do.

“Most parents are just happy to get the food on the table,” says Fisher. “An appealing part of the findings is that they’re relatively straightforward: serve on salad plates.”